Radiation from cellular phones harms the DNA in human cells, according to an extensive, pan-European laboratory study.

The researchers found that levels of radiation equivalent to those from a phone prompted breaks in individual strands of DNA in a variety of human cells. These types of damage have been linked with cancer. The level of injury increased with the intensity of radiation and the length of exposure.

The researchers also saw hints, but not conclusive evidence, of other cell changes, including damage to chromosomes, alterations in the activity of certain genes and a boosted rate of cell division.